Computational studies on carbon nanostructures encapsulating metal atom clusters are proposed. This work is intended to aid the design of novel pharmaceutical nanodevices, namely Magnetic Resonance Imaging (MRI) and X-ray Imaging contrast agents as well as radiopharmaceuticals used for diagnostic or therapeutic purposes. These systems consist of closed shell carbon clusters enclosing metal atom or metal cluster cores as exemplified by recently detected metallofullerenes of composition MxSc3-xN@CN (x = 0-2) and (M1)X(M2)3- XN@CN (x = 1-3) where M, MI, M2 are lanthanide atoms and N = 68, 80. As suggested by experimental assessment, these complexes may provide safer and more efficient Pharmaceuticals for MRI, X-ray and radiographic applications than the commonly utilized metal - chelate compounds. Small clusters of magnetic metal atoms have been shown to exhibit significantly higher magnetic effects than single atoms. This makes carbon nanostructures encaging these clusters interesting candidates for MRI contrast agents. Similarly, a cluster of heavy lanthanide atoms confined by a fullerene shell will generate high X-ray contrast, as first test measurements have demonstrated. Further, radiopharmaceuticals based on fullerenes with radioactive metal cluster cores are envisaged as well as multifunctional species that contain core atoms with high magnetic moments, high atomic numbers and suitable radioactive decay properties. These current pioneering activities in the areas of mass-spectrometric experiment as well as pharmaceutical design can greatly benefit from computational simulations that aim at an in-depth understanding of the respective nanosystems from first principles. Thus, it is planned to use a variety of Density Functional Theory (DFT) procedures to interpret the carbon nanostructures with endohedral metal clusters identified in the laboratory. The proposed research will include metallofullerenes as well as carbon nanotubes enclosing 3d transition metal atom substructures. The in-depth understanding of these species from first principles will make it possible to propose novel units that optimally satisfy the requirements of MRI, X-ray Imaging, radiographic treatment or a combination of these three areas of clinical application.